David Miliband today described China as the 21st century's "indispensable power" with a decisive say on the future of the global economy, climate change and world trade.

The foreign secretary predicted that over the next few decades China would become one of the two "powers that count", along with the US, and Europe could emerge as a third only if it learned to speak with one voice.

The remarks, in a Guardian interview, represented the most direct acknowledgement to date from a senior minister, or arguably from any western leader, of China's ascendant position in the global pecking order.

Miliband said a pivotal moment in China's rise came at the G20 summit last month in London. Hu Jintao, China's president, arrived as the head of the only major power still enjoying strong growth (expected to be 8% this year), backed by substantial financial reserves.

"The G20 was a very significant coming of economic age in an international forum for China. If you looked around the 20 ­people sitting at the table … what was striking was that when China spoke everybody listened," Miliband said.

"China's indispensability in part comes from size, but a second part is that it wants to play a role."

Hu helped bolster Gordon Brown's ­position against protectionism, and ­China's economic stimulus package (equivalent to 16% of its GDP over two years) is widely seen as among the world's best hopes for a recovery.

"Historians will look back at 2009 and see that China played an incredibly important role in stabilising global capitalism. That is very significant and sort of ironic," Miliband said. "There's a joke that goes: 'After 1989, capitalism saved China. After 2009, China saved capitalism.'"

Signals from Beijing since the ­London summit that it is considering tough ­concerted action to reduce CO2 emissions, have raised hopes of reaching a ­workable international pact to contain climate change.

Miliband compared China's potential role in the coming years to the role the US claimed for itself in the 20th century, recalling a 1998 boast by Madeleine Albright, then US secretary of state.

"China is becoming an indispensable power in the 21st century in the way Madeleine Albright said the US was an indispensable power at the end of the last century," Miliband said. "It has become an indispensable power economically, and China will become an indispensable power across a wider range of issues."

But in contrast to America's 20th-century ascent, which eclipsed Britain, Miliband said China would not displace the US but rather join it at "the new top table", and because of its low per capita income, it would not rival the US as the world's leading superpower for at least a generation.

At the G20 summit, some commentators argued that the most important axis was a "G2" of the US and China. Whether that could be expanded to a "G3", Milband argued, would be up to Europe.

"I think that there is a scenario where America and China are the powers that count," the foreign secretary said. "It is massively in our interests to make sure that we have a stake in that debate, and the most effective way of doing so is … to ensure we do it with a European voice."

A report by the European Council on Foreign Relations argued that China was exploiting the EU's divisions and treating it with "diplomatic contempt". The report, published in advance of Wednesday's EU-China summit in Prague, said that European states, dealing with China individually, lacked leverage on issues such as trade, human rights and Tibet.

"Europe has not been sufficiently strategic in its relationship with China," Miliband said. "I think a significant part of that is institutional. The EU-China relationship is a good case for the Lisbon treaty. At the moment, at every EU-China summit, the EU side is led by a different presidency and every year there's a different set of priorities.

"Miliband denied Britain had allowed human rights to slide down the agenda with China, saying there was a constant dialogue between the two countries on the issue. "It's a mature relationship that does take these issues seriously," he said.